The present invention relates to die cutting machines for making carton blanks, and more particularly to a presser assembly for supporting carton blanking scrap during a blanking operation in a die cutting machine.
In the manufacture of cartons, small sheets of paper material having specific profiles are cut out of larger sheets of paper material. These smaller sheets are known as carton blanks which, in turn, are formed into cartons and/or boxes. The blanks are formed during a process known as a blanking operation in a die cutting machine.
In a die cutting machine, the blanks are cut, but not removed from a large sheet of paper material. After the blanks have been cut, the sheet is moved downstream in the die cutting machine to a blanking station where the sheet is positioned over a frame for support. The frame includes large openings which correspond in size, in shape and in position to the profile of the carton blank previously cut. Below the frame is a mechanism for stacking the carton blanks.
At the blanking station, an upper tool is used in combination with the lower tool or frame to knock the carton blanks from the sheet of paper material while holding the scrap material that surrounds the blanks. The upper tool has a support board that moves vertically up and down in the die cutting machine, and the support board typically has a plurality of stand-offs depending therefrom that hold pushers spaced beneath the board which in turn are used to push the carton blanks from the sheet through the lower tool or frame. A plurality of presser assemblies are also mounted in the support board and depend therefrom to hold the scrap material against the lower tool or frame during the blanking operation so that the blanks may be pushed from the sheet. A presser assembly typically includes a presser rail which is biased downwardly away from the support board by a spring so that the rail is positioned slightly below the pushers. As the upper tool is lowered, the presser rail engages the sheet of paper material first such that a scrap portion of the large sheet of material is secured between the presser rail and the frame. The upper tool then continues to be lowered such that the pushers engage the carton blanks and knock the blanks out of the sheet of material. The carton blank then falls into a stacking mechanism below the frame where the blanks are stacked for further processing.
In order to securely hold the carton blank scrap, the present day presser rails are interconnected to the support board by a plurality of guide cylinders. Each guide cylinder biases the presser rail downwardly away from the support board, and are mounted to the support board such that their upper ends project upwardly from the board. However, it is desirable to eliminate any components projecting above the support board and instead provide flush mounted presser assemblies for at least two reasons. First, for tool storage purposes an upper tool having flush mounted pressers takes up less space. This is particularly advantageous in locations where storage space is at a premium. Secondly, many die cutting machines are built in such a manner that the upper tool slides into the blanking station of the machine. Any component projecting upwardly of the support board would interfere with such sliding action. Therefore, only flush mounted presser assemblies can be used with such systems.